Standstill Monitoring; Clamping Monitoring - Siemens SINUMERIK 808D Function Manual

● Positioning window (exact stop fine), position monitoring time, and position controller gain have not been coordinated -->
change machine data:
MD36010 STOP_LIMIT_FINE (exact stop fine),
MD36020 POSITIONING_TIME (exact stop fine delay time),
MD32200 POSCTRL_GAIN (servo gain factor)
Rule of thumb
● Positioning window large --> max. position monitoring time can be set to a relatively short value
● Positioning window small --> max. position monitoring time must be set to a relatively long value
● Position controller gain low --> max. position monitoring time must be set to a relatively long value
● Position controller gain high --> max. position monitoring time can be set to a relatively short value
Note
The size of the positioning window affects the block change time. The smaller the tolerances that are selected, the longer
the positioning action will take, which in turn means a longer time before the next command can be executed.
4.2.3

Standstill monitoring

Function
At the end of a motion block (position setpoint has reached target), a check is made as to whether the axis is not more than
the distance specified in MD36060 STANDSTILL_POS_TOL (standstill tolerance) away from its setpoint after the
configurable delay time in MD36040 STANDSTILL_DELAY_TIME (standstill monitoring delay time) has expired. Otherwise,
an alarm will be triggered.
Effectiveness
Standstill monitoring is always active after "Standstill monitoring delay time" active has expired, as long as no new travel
command is present.
Standstill monitoring is active on axes and position-controlled spindles.
Effect
When the monitoring function responds, it has the following effects:
● Alarm 25040 "Standstill monitoring" is triggered
● The affected axis/spindle is brought to a standstill with rapid stop (with open position control loop) along a speed setpoint
ramp. The braking ramp time is set in
MD36610 AX_EMERGENCY_STOP_TIME (duration of the braking ramp for error states).
● If the axis/spindle is involved in interpolation with other axes/spindles, these are stopped by rapid stop with following
error reduction (default for position partial setpoint = 0).
Cause of error / remedy
● Position control gain too high (control loop oscillation) --> change machine data for control gain MD32200
POSCTRL_GAIN (servo gain factor)
● Standstill window too small --> change machine data
MD36030 STANDSTILL_POS_TOL (standstill tolerance)
● Axis is mechanically "pushed" out of position --> eliminate cause
4.2.4

Clamping monitoring

Function
If the axis must be clamped once it has been positioned, the clamping monitoring function can be activated via IS "Clamping
in progress" (DB380x.DBX2.3).
This may be necessary as the axis can be forced further from the setpoint than the standstill tolerance permits during the
clamping process. The amount by which the axis may leave the command position is specified in MD36050
CLAMP_POS_TOL (clamping tolerance for interface signal "Clamping active").
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Function Manual
01/2017